1. Field of the Invention
The present invention pertains in general to a method and apparatus for counting a stream of articles as they are transported or allowed to fall through a passageway. More particularly, the invention pertains to a method and apparatus for counting irregularly shaped articles using a pair of crossed light beams at a sensing plane in the above referenced passageway. Most particularly, the invention pertains to an improved method and apparatus for counting irregularly shaped articles that allows counting the articles by volumes and partial volumes, three dimensional imaging of the articles being counted, and ability to adjust to the most efficient counting speed.
2. Description of the Related Art
Using a beam of light to count articles as they pass through a passageway has been known for many years. For example, U.S. Pat. Nos. 3,618,819; 4,982,412; and 4,675,520 all disclose article counters that employ a beam of light across a passageway wherein the articles, as they traverse the passageway, in some manner, block the beam of light. This, in turn, provides information that enables counting of number of articles. However, these article counters did not accurately count or sense unsymmetrical articles.
Several years ago, an improved article counting apparatus and method was developed to address these deficiencies. U.S. Pat. Nos. 5,313,508 and 5,454,016 disclose a counting apparatus and method for counting articles that employs a pair of light sources that provide light beams that are substantially perpendicular to one another along planes of a passageway through which the articles being counted traverse. As an article passes the light sources, each source provides a separate sensing of the article. Therefore, symmetry of an unsymmetrical article is irrelevant, as one angle of light source will xe2x80x9csensexe2x80x9d the greater surface area portion of the article, allowing it to be accurately counted. This apparatus and method improved upon the systems noted above by providing a system that accurately counted unsymmetrical articles traversing a passageway.
However, while the system described above allows for more accurate counting of unsymmetrical articles, it still possesses significant limitations in counting articles. For instance, the system does not allow for counting and batching of articles that comprise different volumes, for example, articles that are broken. The above system also does not allow for any type of visualization of the articles being counted. Finally, the system only allows for rudimentary estimate of the appropriate feed rate of articles to be counted. For instance, if the feed rate for items is too fast, providing for insufficient space between the articles being counted, the first article in a xe2x80x9cnewxe2x80x9d batch, could be damaged by the gate which closes between batches.
Therefore, it is desired to provide an improved apparatus and method for counting articles that allows unsymmetrical articles to be counted by volume or partial volume, allows the articles to be three dimensionally imaged as the articles traverse the apparatus, and allows the apparatus to sense the most efficient throughput counting speed for the particular articles being counted.
The present invention comprises improvements to the methods and apparatuses disclosed in U.S. Pat. Nos. 5,313,508 and 5,454,016 which are incorporated by reference herein.
Accordingly, it is an object of this invention to provide a device and method that allows unsymmetrical articles to be counted by volume and partial volume.
It is a further object of this invention to provide a device and method that allows counted articles to be visually displayed, either immediately after the articles pass through the counter or at some later time.
A still further object of this invention is to provide a device and method that calculates the distance between unsymmetrical articles being counted, and, using this information, to adjust the feed rate of said articles to a selected feed rate.
This invention accomplishes these objectives and other needs related to counting and batching unsymmetrical articles by providing an improved method to count and batch articles of an arbitrary shape and size. The articles travel through a passageway past at least a pair of orthogonally positioned light sources and respective orthogonally positioned light detectors. These light sources and detectors are positioned to provide crossing light beams that extend across the passageway at a detection station. The light sources are operated alternately as the articles pass through the detection station. This allows the user to obtain a plurality of article scans by sensing the quantity of light that is detected by each light detector and providing electrical signals representative of the amounts of light received by the respective light detectors. These electrical signals are then stored along with the times corresponding with each signal. An actual volume is obtained for each article and the actual volume is compared to a predetermined volume for each article to obtain a count portion. This allows the user to count articles that are broken or not whole, complete articles. Finally, the count portions of each article are added together to obtain a total batch volume. This total batch volume should be more of an exact batch volume than those obtained in previous counting methods due to using actual volumes versus estimated volumes.
Other embodiments of the method include steps related to using cross sectional area scans of the articles in order to provide a three dimensional view of scanned articles on some type of screen as well as measuring the distance between articles and using this information to vary the feed rate of the articles to an optimum rate.